A conventional golf club head comprises a main body 10 and a striking plate 20, as shown in FIGS. 1 and 2. The main body 10 is a wood golf club, which is provided with an opening 11 and a stepped portion 12. The stepped portion 12 is formed around an inner rim of the opening 11 for supporting a lip area around an outer periphery of a inner face of the striking plate 20, so that the main body 10 and the striking plate 20 can be placed together for welding. Referring to FIG. 2, it is a further option that the outer periphery of the striking plate 20 can be bent to form a ring wall 21 so that a striking area of the striking plate 20 is increased.
Applying a welding means to combine the main body 10 and the striking plate 20, the inner rim around the opening 11 of the main body 10 (namely, the welding seam) is constituted a curve that is varied in two-dimensional or three-dimensional space. To weld the main body 10 and the striking plate 20, a welding machine must be preset a welding path in multi-dimensions corresponding to the curve of the main body 10. However, in high-energy welding, a sophisticated welding path may result in a specific decrease in control of welding depth. As a result, the utilization of a relatively high energy welding means for assuring adequate welding depth may easily cause overflow of melting metal (molten metal) intruding into the interior of the main body 10. The intruded melting metal is solidified and attached to an interface between the main body 10 and the inner face of the striking plate 20, which reduces the effective elastically deforming area of the striking plate 20 and therefore the coefficient of restitution, COR, thereof. This also affects the appearance of the main body 10. It is a further disadvantage that the intruded melting metal may fall into the interior of the main body 10 and result in flux beads that cause striking noises and disturbance while wielding a golf club. Moreover, an iron type of the golf club head is usually provided with a cavity at its rear portion. An undercut portion is formed between the cavity and a striking plate. The intruded melting metal will be solidified in the undercut portion and it is difficult to remove. This also affects the coefficient of restitution of the striking plate.
Alternatively, the utilization of a relatively lower energy welding means can avoid the intrusion of overflow of the melting metal, but it may result in an inadequate welding depth that may weaken the entire structure of the golf club head. To prevent melting metal intrusion, a conventional golf club head commonly adopts an enlarged contact area between the striking plate 20 and the stepped portion 12 of the main body 10, which also reduces the effective area of elastic deformation of the striking plate 20. Therefore, it is necessary to improve the structure of conventional golf club heads.
Accordingly, the present invention provides a golf club head whose main body is provided with an inner rim of an opening formed with a first stepped portion and a second stepped portion. The first stepped portion and the second stepped portion define a groove therebetween. When the striking plate is combined with the main body by welding, the groove of the main body can obstruct an overflow of melting metal from a welding seam between the main body and the striking plate. This enhances welding quality and thereby overcomes the problem of club head noises and disturbance caused by flux beads remained the main body. Further, the first stepped portion supports the striking plate with a reduced contact surface area so as to increase the effective elastically deforming area of the striking plate and thereby the striking distance of a golf club.